Effects of TeOx films on temperature coefficients of delay of Love-type wave devices based on TeOx/36°YX-LiTaO3 structures

Tellurium oxide (TeOx) thin films are prepared on 36°YX-LiTaO3 substrates by RF magnetron sputtering technique under different deposition conditions. The structures and compositions of the TeOx films are analyzed by X-ray diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, which show that the TeOx films are amorphous and with different ratios of Te to O prepared in different conditions. Then the Love-type wave devices based on TeOx/36°YX-LiTaO3 structures are fabricated, and the temperature coefficient of delay (TCD) of the Love-type wave devices are investigated. The results show that, when TeOx films deposited at suitable deposition conditions, the TCD of the Love-type wave devices are less than that of the shear-horizontal (SH) wave devices fabricated on the bare 36°YX-LiTaO3 substrates, which demonstrates that the TCD of the TeOx films is negative. Moreover, the TCD of the devices are strongly dependent upon the preparation conditions and the thicknesses of the TeOx films. Therefore, the TCD of the Love-type wave devices can be optimized by suitably selecting the preparation conditions and the thickness of TeOx films.